/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef nsDocShellEnumerator_h___
#define nsDocShellEnumerator_h___

#include "nsISimpleEnumerator.h"
#include "nsTArray.h"
#include "nsIWeakReferenceUtils.h"

class nsIDocShellTreeItem;

/*
// {13cbc281-35ae-11d5-be5b-bde0edece43c}
#define NS_DOCSHELL_FORWARDS_ENUMERATOR_CID  \
{ 0x13cbc281, 0x35ae, 0x11d5, { 0xbe, 0x5b, 0xbd, 0xe0, 0xed, 0xec, 0xe4, 0x3c } }

#define NS_DOCSHELL_FORWARDS_ENUMERATOR_CONTRACTID \
"@mozilla.org/docshell/enumerator-forwards;1"

// {13cbc282-35ae-11d5-be5b-bde0edece43c}
#define NS_DOCSHELL_BACKWARDS_ENUMERATOR_CID  \
{ 0x13cbc282, 0x35ae, 0x11d5, { 0xbe, 0x5b, 0xbd, 0xe0, 0xed, 0xec, 0xe4, 0x3c } }

#define NS_DOCSHELL_BACKWARDS_ENUMERATOR_CONTRACTID \
"@mozilla.org/docshell/enumerator-backwards;1"
*/

class nsDocShellEnumerator : public nsISimpleEnumerator
{
protected:
  enum
  {
    enumerateForwards,
    enumerateBackwards
  };

  virtual ~nsDocShellEnumerator();

public:
  explicit nsDocShellEnumerator(int32_t aEnumerationDirection);

  // nsISupports
  NS_DECL_ISUPPORTS

  // nsISimpleEnumerator
  NS_DECL_NSISIMPLEENUMERATOR

public:
  nsresult GetEnumerationRootItem(nsIDocShellTreeItem** aEnumerationRootItem);
  nsresult SetEnumerationRootItem(nsIDocShellTreeItem* aEnumerationRootItem);

  nsresult GetEnumDocShellType(int32_t* aEnumerationItemType);
  nsresult SetEnumDocShellType(int32_t aEnumerationItemType);

  nsresult First();

protected:
  nsresult EnsureDocShellArray();
  nsresult ClearState();

  nsresult BuildDocShellArray(nsTArray<nsWeakPtr>& aItemArray);
  virtual nsresult BuildArrayRecursive(nsIDocShellTreeItem* aItem,
                                       nsTArray<nsWeakPtr>& aItemArray) = 0;

protected:
  nsWeakPtr mRootItem;  // weak ref!

  nsTArray<nsWeakPtr> mItemArray;  // flattened list of items with matching type
  uint32_t mCurIndex;

  int32_t mDocShellType;  // only want shells of this type
  bool mArrayValid;  // is mItemArray up to date?

  const int8_t mEnumerationDirection;
};

class nsDocShellForwardsEnumerator : public nsDocShellEnumerator
{
public:
  nsDocShellForwardsEnumerator()
    : nsDocShellEnumerator(enumerateForwards)
  {
  }

protected:
  virtual nsresult BuildArrayRecursive(nsIDocShellTreeItem* aItem,
                                       nsTArray<nsWeakPtr>& aItemArray);
};

class nsDocShellBackwardsEnumerator : public nsDocShellEnumerator
{
public:
  nsDocShellBackwardsEnumerator()
    : nsDocShellEnumerator(enumerateBackwards)
  {
  }

protected:
  virtual nsresult BuildArrayRecursive(nsIDocShellTreeItem* aItem,
                                       nsTArray<nsWeakPtr>& aItemArray);
};

#endif // nsDocShellEnumerator_h___
